1. Field of the Invention
The invention relates to a steel plate having good resistance to a corrosive atmosphere, containing weakly acidic (pH 3.5 to 5.5) condensed water comprising SO.sub. 2, Cl.sup.- ion and CO.sub.2, in a power station which burns LNG, etc.
2. Description of the Related Art
An exhaust gas from a boiler which burns LNG contains SO.sub.2, Cl.sup.- ions, CO.sub.2 and a water vapour component, with the result that condensed water is brought into existence between the bailer and the funnel due to a drop in the exhaust gas temperature. The condensed water is a weakly acidic (pH 3.5 to 5.5) and contains dissolved SO.sub.2, Cl.sup.- ions and CO.sub.2, and is highly corrosive. Previously, a stainless steel and carbon steel have been used, as a steel material, in an atmosphere producing this corrosive condensed water.
For instance, in the case of stainless steels, Unexamined Japanese Patent Publication (Kokai) No. 1-165752, discloses a method in which a ferritic stainless steel comprising 14 to 21% of Cr, Ni, Cu, Mo, etc., and having a corrosion resistance in halogenide compounds can be used. In case of carbon steels, Unexamined Japanese Patent Publication (Kokai) No. 1-306585 discloses a method in which the corrosion can be prevented by adding a corrosion inhibitor into the solution in contact with the steel.